The present invention relates to a method and apparatus for forming a visible image on an optical disk by use of a laser beam to the surface of an optical disk, such as a CD-R/RW, a DVD+R/RW or a DVD-R/RW.
It is known to form a visible image, such as a character and a figure, onto the recording surface or the label surface (opposite surface to the recording surface) of an optical disk by use of a laser beam.
For example, Patent Document 1 proposes to provide a visible-light-characteristic change layer in a position to be seen from the label side of the optical disk so that a visible image can be formed by changing the visible-light characteristic by application of a laser beam.
Patent Document 2 proposes to use a reversible phase-change material in a recording layer of the optical disk that can record a visible image by use of a laser beam so that the figure being recorded can be rewritten.
Patent Document 3 proposes to newly, additionally write a visible image onto the recording surface of an optical disk already formed with a visible image.
Patent Document 4 proposes a barcode that can be suitably formed on the optical disk surface.
Patent Document 1 JP-A-2002-203321
Patent Document 2 JP-A-2003-016649
Patent Document 3 JP-A-2004-039019
Patent Document 4 JP-A-2004-063030
As described above, Patent Document 3 proposes to additionally write a visible image further to the surface of the optical disk on which a visible image is already formed by means of a laser beam.
However, in the Patent Document 3, the manner and sequence in additional image formation is fixed previously so that the user is not allowed to make an addition in a free manner.
For adding a visible image, it is necessary to recognize the on-disk-surface position of the visible image already formed, in order to prevent against the overlap of the image newly recorded with the existing image and against the occurrence of a useless space.
For this reason, Patent Document 3 proposes (1) a method to detect a positional address from the wobble formed on the disk, to thereby record a start or end address of the visible image recorded, and (2) a method to form an area a visible image is formed from the envelope form in a reflection light signal.
However, in the method of (1), there is a need to provide a groove in the area where to record a visible image in order to detect the positional address. Meanwhile, in the method (2), despite there is a difficulty in detecting a position accurately, especial accuracy is not needed because the position, sequence and shape is fixed previously.